In recent years, many liquid crystal display devices capable of performing 3D display (stereoscopic vision) such as 3D television devices have been on the market. In a liquid crystal display device adopting a frame-sequential method which is one of the methods for achieving 3D display, a left-eye image and a right-eye image are alternately displayed on a liquid crystal panel every predetermined period of time (e.g., every 1/120 second) and the lenses of active shutter glasses alternately open and close one at a time in synchronization with the display. In this manner, an image with parallax between left and right eyes is visually recognized, and accordingly, a viewer perceives the image as a stereo image.
As for liquid crystal display devices capable of performing 3D display, a reduction in crosstalk is a conventional issue. Crosstalk is a phenomenon where a left-eye image is also captured by a viewer's right eye and a right-eye image is also captured by a viewer's left eye, and accordingly, an image where the left-eye image and the right-eye image overlap each other is visually recognized.
Now, the occurrence of crosstalk will be described with reference to FIGS. 19 and 20. FIG. 19 is a diagram showing an ideal change in luminance for when 3D display is performed. FIG. 20 is a diagram showing an actual change in luminance for when 3D display is performed. Note that in FIGS. 19 and 20, the horizontal axis represents time, and the vertical axis represents luminance. Note also that reference character TL indicates a left-eye image display period, and reference character TR indicates a right-eye image display period. When a frame-sequential method is adopted, liquid crystal molecules are driven such that, as described above, a left-eye image and a right-eye image are alternately displayed. If the target luminance of the left-eye image in a certain region is Lu(R) and the target luminance of the right-eye image in the region is Lu(L), then ideally the luminance should change as shown in FIG. 19. If the luminance changes as shown in FIG. 19, crosstalk does not occur. However, since liquid crystal responsiveness is not good, in practice the luminance changes as shown in FIG. 20. Specifically, at switching timing between left-eye image display and right-eye image display, the luminance changes in a delayed manner compared to the ideal change. In FIG. 20, a hatched portion indicated by reference character 90 indicates a period during which the target luminance is not reached due to a delay in change in luminance. Due to the difference between the actual luminance and the target luminance during this period, crosstalk occurs.
For measures to suppress a reduction in image quality caused by crosstalk such as that described above, an improvement in the drive frequency of a liquid crystal panel, an improvement in the control of light emission of an LED backlight, an improvement in liquid crystal response speed, etc., are conventionally performed.
Note that in connection with this invention, Japanese Patent Application Laid-Open No. 2005-242026 describes implementation of a high image quality liquid crystal display that is provided with high-speed responsiveness and high gray scale representation capability by combining overshoot drive that forcefully allows liquid crystal to respond at high speed, and a pseudo-multi-gray-scale technique for increasing the number of display gray scales by applying noise. Detailed description of the overshoot drive will be provided later.